1. Field of the Invention
The present invention relates to a color filter array of an image sensor, and more particularly to a method for correcting pixel information of color pixels on a color filter array of an image sensor.
2. Background of the Invention:
CMOS Image Sensor (CIS) is an imaging device that performs the role of an electronic film in digital photography equipment. CIS has been used in a broad range of areas including digital cameras, camera phone, web-camera, notebook security devices, automobile, and miniature imaging devices used in medical applications. To achieve high image sensing quality, it is necessary for the CIS to provide wide dynamic range and high sensibility.
A CIS includes a color filter array, a micro lens array and pixel sensors (e.g., a photo diodes). A color filter array is a mosaic of tiny color filters placed over the pixel sensors of the image sensor to capture color information. A Bayer filter array is a typical color filter array for arranging RGB (red, green, blue) color filters on a square grid of photo diodes.
In order to increase the image sensibility of the CIS, a plurality of possible color filter arrays with WRGB (white, red, green, blue) arrangement have been proposed. For example, Toshiba proposed a 1/4 WRGB color filter array having a plurality of pixel arrays. As shown in FIG. 1A, each pixel array consists of a four (4) 2×2 pixel units, and each 2×2 pixel unit has one (1) white pixel, one (1) red pixel, one (1) green pixel and one (1) blue pixel.
After TSB proposed the 1/4 WRGB color filter array, Eastman Kodak Company proposed a 2/4 WRGB color filter array having a plurality of pixel arrays. As shown in FIG. 1B, each pixel array consists of a four (4) 2×2 pixel units, and each 2×2 pixel unit has two (2) white pixels and two (2) color pixels with the same color.
Since the 1/4 WRGB color filter array has one (1) white pixel in each pixel unit of the color filter array, the image sensitivity of the 1/4 WRGB color filter array is higher than a typical Bayer filter array. Similarly, since the 2/4 WRGB color filter array has two (2) white pixels in each pixel unit of the color filter array, the image sensitivity of the 2/4 WRGB color filter array is higher than a typical Bayer filter array and 1/4 WRGB color filter array. However, the image resolution of the CIS with the 2/4 WRGB color filter array will be reduced, also due to the increased number of white pixels in the 2/4 WRGB color filter array. Therefore, the more number of the white pixels in a color filter array, the higher the image sensitivity of the CIS and the lower the image resolution of the CIS.